Users of existing syringes generally must visually measure the medication level being drawn from a container into the syringe using scale markings while the dose is being drawn. The plunger is drawn axially and rearwardly through a cylindrical tube, or barrel, of the syringe to create suction within the barrel to draw liquid medication from a container into the syringe. The axial distance the plunger moves rearwardly determines the volume of the medication drawn into the syringe. The medication is then dispensed by moving the plunger forward through the barrel. The scale markings on the barrel facilitate the user drawing the desired dosage.
The amount of dose is determined by the volume of liquid medication drawn into the syringe, and the scale markings run perpendicularly to the longitudinal axis of the syringe. The scale markings and graduation lines are typically closely spaced. Thus, the scale markings can be difficult to read, making drawing an accurate dose difficult. Accordingly, a need exists for a syringe in which the dose setting is easily viewable and determinable.
Furthermore, a precise dose requires the piston to be moved a small distance. The break-away (static friction) required to begin plunger movement is greater than the glide-force (dynamic friction) required once the plunger has begun moving. Thus, it is easy for a user to over-shoot a desired dose setting when precise movement is required, which often results in the user repeatedly moving the plunger above and below the desired dose setting. Accordingly, a need exists for a syringe in which the desired dosage is easily obtainable.
The user ultimately determines the amount of liquid medication drawn into the syringe. Thus, when the user is not being careful, too little or too much medication can be drawn into the syringe. Accordingly, a need exists for a syringe in which an accurate dose is easily drawn into the syringe.